SerialTools does not receive any data from the port, but I know data is coming in.

Upgrade to SerialTools v1.11 or later.

Try to set Port.DTR to true. Some devices and terminal programs demands that to send data to the PC / Pocket PC.

Make sure you set Port.BufferSize to 0 (default). Port.OnRead will not be called until BufferSize bytes has been received, and Port.Read will not return until BufferSize bytes has been received. Setting BufferSize to 0 disables that function.